Lactococcus lactis YfiA is necessary and sufficient for ribosome dimerization

Area of Science:

• Microbiology
• Molecular Biology
• Structural Biology

Background:

• Ribosome inactivation and dimerization in Escherichia coli involve ribosome modulation factor (RMF) and hibernation promotion factor (HPF).
• Lactococcus lactis MG1363 utilizes a protein, YfiA(L), for ribosome dimerization during stationary phase growth.

Purpose of the Study:

• To investigate the role and mechanism of YfiA(L) in Lactococcus lactis ribosome dimerization.
• To compare the process of ribosome dimerization and inactivation between Lactococcus lactis and Escherichia coli.

Main Methods:

• Heterologous expression and in vitro assembly of ribosome dimers.
• Gene deletion studies to assess the function of YfiA.
• Single particle electron microscopy for structural analysis of ribosome dimers.

Main Results:

• Full-length YfiA(L) is necessary and sufficient for ribosome dimerization in L. lactis and functions heterologously in E. coli.
• Deletion of the yfiA gene impairs L. lactis survival under energy-starving conditions.
• Structural analysis revealed distinct monomer association in L. lactis ribosome dimers compared to E. coli.

Conclusions:

• Ribosome dimerization and inactivation pathways differ significantly between L. lactis and E. coli at cellular and molecular levels.
• The YfiA protein, with its unique C-terminal domain, plays a distinct role in bacterial ribosome regulation and stress survival.